I built my new PC with old video card as below. But it always random black screen in low workload.Play game, burn in video card, cpu, etc., no black screen.NO OC. Even lock CPU at 3.7GHz, memory 2133mhz

My build:

AMD Ryzen 2700x

Prime X470 pro BIOS 4011 / 4008

g.skill f4-3200c16d-16gtzr

AMD R7 370 4G HDMI to TV, DP to monitor

EVGA G3 550W

Win 10 Pro x64 1803

I thought it's memory issue and RMAed Mobo and memory. The issue still there.

I swapped the PSU, the issue still there.

Reinstall win 10, issue still there.

Install win 10 on M.2 or sata ssd , issue still there.

changed DP, HDMI cable, still black screen.

Tried Mobo BIOS 4008, 4011, 4018, 4008 is most stable, few chance of black screen. But still black screen.

Boy you got a good question there. It could be that for whatever reason on the one system you just need a bit more power ceiling for the card. So try this:

Radeon Settings/Gaming/Global Settings/Global Wattman: Find the "Power Limit" Slider and move it to it maximum.

If this doesn't help I think you are right and have either a driver issue, bios issue (is that up to date on the new motherboard?) or other hardware issue. At that point I would open a support ticket with Saphire or with AMD if they can't help. The link for AMD is on the contact us page of their website at the bottom.